Abstract
Polymers are widely used in various industries because of their characteristics such as elasticity, abrasion resistance, fatigue resistance and low temperature. In particular, the tensile characteristic of rubber composites is important for the stability of industrial equipment because it determines the energy absorption rates and vibration damping. However, when a product is used for a long period of time, polymers become hardened owing to the changes in characteristics because of aging, thereby reducing the performance and increasing the possibility of accidents. Therefore, accurately predicting the mechanical properties of polymers is important for preventing industrial accidents while operating a machine. In general reactions, the linear Arrhenius equation is used to predict the aging characteristics; however, for rubber composites, it is more accurate to predict the aging characteristics using nonlinear equations rather than linear equations. However, the reason that the characteristic equation of the polymer appears nonlinear is not well known, and studies on the change in the characteristics of the natural and butadiene rubber owing to degradation are still lacking. In this study, a tensile test is performed with different aging temperatures and aging time to evaluate the aging characteristics of rubber composites using strain energy density. We propose a block effect of crosslink structure to express the nonlinear aging characteristics, assuming that a limited reaction can occur owing to the blocking of reactants in the rubber composites. Consequently, we found that a relationship exists between the crosslink structure and aging characteristics when the reduction in crosslink space owing to aging is represented stochastically. In addition, a modified Arrhenius equation, which is expressed as a function of time, is proposed to predict the degradation rate for all aging temperatures and aging times, and the formula is validated by comparing the degradation rate obtained experimentally with the degradation rate predicted by the modified Arrhenius equation.
Highlights
Rubber composites are widely used in industrial components because of their good energy-absorbing properties, resilience, elasticity and high extensibility
In a vibrating machine, the role of rubber that supports the body of the structure and absorbs vibrations and shocks generated from the ground is crucial. [1,2] In addition, the tensile characteristic of rubber composites determines the energy absorption rates and vibration damping, which is an important factor for the stability of an industrial equipment
Tensile tests were conducted to obtain stress–strain curves with four strain values
Summary
Rubber composites are widely used in industrial components because of their good energy-absorbing properties, resilience, elasticity and high extensibility. We attempt to evaluate the degradation characteristics of rubber composites by performing tensile tests [11] on the rubbers at various aging temperatures and aging times. For this purpose, strain energy densities (SED) [12,13] were used and the tensile properties and SED values of rubber materials with varied degradation conditions were compared and analyzed [14]. By applying the modified Arrhenius equation, we derived the relationship between short-term high-temperature aging and long-term low-temperature aging, and suggest a method for predicting the degradation rate of rubber composites under all aging conditions. The accuracy of the formula was demonstrated by comparing the actual experimental results obtained using an aged specimen with the calculated degradation rates predicted by the modified Arrhenius equation
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